Recent studies have shown that light has surprising neuroendocrine and anti-depressant effects in humans. Prompted by these findings, a UCSD group has three times replicated a 1967 study by Dewan, showing that an ordinary bedside light can influence menstrual cyclicity. Before we can even begin to research the parameters of light effects in reproductive medicine, however, more sophisticated lighting devices are needed. In this Phase I application, we will develop a bedside NiteLite lighting device suitable for application to menstrual problems, validate the electronic functioning of the instrument, and demonstrate the effectiveness of the instrument in altering menstrual cyclicity. The focus of Phase I is electronic device development. Later, in Phase II, we will propose to characterize the endocrine responses of patients to night lights, and to determine the parameters of illumination which produce the most valuable clinical effects.